Thermostatic signal



April 30, 1929. c. F. WENTZEL THERMOSTATIC SIGNAL Filed Aug. 10, 1925 INYENTEIR- 291 W515i ATTEIE EY.

Patented Apr. 30, 1929.

UNITED STATES CARL F. WENTZEL, OF "WHEELING, VIE-ST VIRGINIA,

THERIVIGSTATIC SIGNAL.

Application filed August 10, 1925.

nal system embodying the invention, the casing being shown in top plan;

Figure 2 is an enlarged detail view of the invention, partly in side elevation and partly in section; and

Figure 3 is an enlarged cross-section of the mercury-containing tube.

Referring to said drawings, 1 indicates an air-tight shell or casing, preferably of rectangular box-like form. Suspended within said casing is a container 2 of bulb-like form,

preferably made of glass, the upper end portion of said container being closely fitted in an openin provided therefor in the topmost wall of said casing. Said container has mounted within the lower portion thereof a receptacle 3 which, as herein shown for illustrative purposes, is of inverted cone form and which is preferably made of hard rubber. Fixed within said receptacle at or adjacentto its bottom are two separated metal contacts 4t and 5 from which lead conductor wires 6 and 7-, respectively, forming part of a normally open electric circuit which includes therein, located at any appropriate signaling point, a bell 8 or other appropriate form of annuciator adapted to be actuated by the closing of said circuit. Said wires 6 and 7 are connected to posts 9 and 10 mounted in a removable cap or cover 11 which is employed as a closure for'the container 2, and said posts are in turn connected by conductors 12 and 13 to the annuciator 8.

Mounted within the container 2 and having one end thereof opening outward through the container wall into the interior of the casing 1 is a tube 14: which is shaped intermediate its ends to form a container-like portion, preferably of depending arcuate form, as shown at 14*. Said tube has its opposite, or inner, end overhanging the receptacle 3, as shown, andthe portion 14 is designed as a Serial No. 49,210.

pocket for a quantity or column of mercury 15.

Disposed within the tube 1 1, which is preferably made of glass, is a length of fine wire 16, or other thread-like filament, which closely underlies the top wall of the arcuate me"- eury-pocketing portion 14: of said tube and which has its opposite ends suit-ably supported as by fusing into the walls of the tube at points above the level of the ends of the mercury column 15, which level is well above that of said top wall, as shown in Fig. 2.

Due to the fact that the mercury column 15 is divided along the engaged tog wall of the tube by the wire or like element 16, and that the mercury of said column is depressed slightly by capillary repulsion between the mercury, the wire and the tube, two minute parallel air courses 17 are afforded in the angles between the Wire and the wall of the tube, as shown in Fig. 3. Said air courses provide restricted avenues of egress from and ingress to the interior of the casing 1 for air as the latter expands and contracts with normal gradual changes of temperature to which it is subjected.

When, however, the air within the casing 1 is expanded rapidly. or at an abnormally high rate, as when a fire occurs adjacent to the casing, the restricted passages 17 are incapable of conducting the increased pressure of air which seeks escape, and the pressure of said air, acting upon the adjacent end of the mercury column, forces the mercury forward, causing it to overflow to the bottom of the receptacle. When the mercury so discharged into the receptacle shall have bridged the space between the contacts l and 5, the elec tric circuit to the annunciator S is instantly closed, resulting in actuation of the latter.

The interior of the container 2 is in open communication with the atmosphere through an opening 18 provided in the cover 11.

It is obvious that numerous changes may be made in the forms and the general arrangement of some of the parts of the apparatus described without departing from the spirit or scope of the invention; hence, I am not to be understood as imposing limitations other than those made necessary by the spe citicterms employed in the appended claims.

hat is claimed is- 1. In a thermostatic signaling device embodying a normally open electric signal circuit including separated contacts, an airtight casing, a receptacle associated with said casing having open communication with the atmosphere, said receptacle having said contacts located therein, a hollow member providing means of communication between the interiors of said casing and said receptacle, said member having a mercury-pocketing portion from which mercury under pressure is overflowable into bridging relation to said contacts for closing said circuit, and means extending through said pocketing portion of said member in contact with a wall of the latter whereby, through capillary repulsion, minute air passages through the pocketed mercury are created.

2. In a thermostatic signaling device embodying a normally open electric signal circuit including separated contacts, an airtight casing, a receptacle associated with said casing having open communication with the atmosphere, said receptacle having said contacts located therein, means providing an avenue of communication between the interiors of said casing and said receptacle, said means including a pocket portion adapted to be occupied by a quantity of mercury and from which mercury under pressure is overflowable into said receptacle for bridging the space between said contacts, and means extending through said pocket portion whereby, through capillary repulsion, are formed minute air passages through the mercury of said pocket portion.

3. In a thermostatic signaling device embodying a normally open electric signal circuit -including separated contacts, an airtight casing, a receptacle associated with said casing having open communication with the atmosphere, said receptacle having said contacts located therein, a tubular member bent downward to form a mereurypocl eting portion intermediate its ends said member having one end opening into said casing and having its opposite end so positioned that mercury over-flowed thcZ-ethrough by the force of thermal expansion of air within the casing will enter and bridge said contacts for closing said circuit, and means extending through said pocketing portion whereby, through capillary repulsion, is formed passages tor the gradual expulsion of air from the casing.

In testimony whereof, I allix my signaturc.

CARL F. VENIZEL. 

